Basics
Antennas for Meshcore in the US generally need to have decent SWR (Standing Wave Ratio) on 910.525mhz. Most 915mhz antennas do. but some have a narrow range where they are resonant and you need to be careful of these.
Connectors
There are various connectors that you may encounter when buying antennas. The most common type you'll find on portable nodes is SMA. This is generally a gold screw that's about 1/4" in diameter with a hole in the middle. If you have external screw threads and a pin in the center, that means you have RP-SMA and make sure to buy only RP-SMA connectors to go with it. The much larger connector you'll encounter is called an N connector. This has external threads on the female side and a hollow gold pin in the middle. The connector that's generally on the LoRa boards is called a U.FL IPEX connector. When building nodes, make sure to get the right pigtail to convert to the type of antenna you want to use.
Options
There are many options for antennas. Here are some that have proven worthy in use for various members of the Inland Northwest Mesh:
| Antenna | Approximate Cost | Link |
|---|---|---|
| GIzont Whip | $7 | https://www.aliexpress.us/item/3256804421300249.html |
| Rokland 5.8dbi Base Antenna | $45 | https://store.rokland.com/products/5-8-dbi-n-male-omni-outdoor-915-mhz-antenna-large-profile-32-height-for-helium-rak-miner-2-nebra-indoor-bobcat |
Measurement
A NanoVNA can be used to measure the SWR of your antenna as long as 910mhz is within its range (usually HIGH channel). https://www.youtube.com/watch?v=pQuFX5r7f1A
Cell Site Considerations
When deploying at a noisy site like a cell site, you'll likely need some sort of equipment to silence the LTE Band 5 noise that will slowly back off your gain until your repeater is deaf. One option is the ACASOM 915 cavity filter although it seems to be very hard to find. Some people are experimenting with cavity filters tuned to the exact frequency needed for meshcore with a 4mhz passband. Ask in discord about that.